A better understanding of cell mediated immunity in man. Particularly, normal or abnormal immunologic mechanisms involved in epithelial and lymphoid malignancies, autoimmune disease, allograft rejection and allergic contact dermatitis. Characterization of the abnormal blastogenic responses found in certain diseases, particularly lymphoid malignancies. The necessity of both lymphocytes and macrophages in blastogenic responses in vitro has been elucidated and the lymphocyte has been identified as the cell which determines the immunologic specificity of the blastogenic response to antigens. A soluble mediator, released by macrophages, has been identified as the cell which determines the immunologic specificity of the blastogenic response to antigens and foreign tissues. Soluble mediators (lymphokines), released by various subpopulations of lymphocytes, have also been detected and studied at varying times following specifically induced cell-mediated contact sensitivity reactions. Our combined in vitro and in vivo controlled methods for the study of cell-mediated immunity in man have allowed us to initiate basic immunopharmacology and immunogenetics approaches for the study of a variety of diseases and has already resulted in several practical diagnostic procedures. Additional studies promise a method for selecting effective immunotherapeutic agents against specific cancers.